Patent GB-345299-A (GB)
Title: An improved electrical equipment for use in connection with the running-in and testing of engines
IPC: G01M15/04
Filed: 1929-12-18
Abstract: 345,299. Electric equipment for runing-in and testing engines. HEENAN & FROUDE, Ltd., Worcester, ELECTRIC CONTROL, Ltd., Brighton, ROSS, E. G., 7, Timberdene Avenue, Worcester, and OXLEY, A. G. H., Mayfield, Radford Road, Leamington Spa. Dec. 18, 1929, No. 38795. [Class 38 (iv).] An electrical equipment for use in the running- in of engines wherein this operation is effected by an electric motor at increasing speeds and means are provided for positively preventing the change from one speed to the next until the frictional resistance of the engine has decreased to a given value. Running-in.-The closure of switch A establishes a circuit from L+ through an isolating switch IS, switch A, series field winding 3, resistances R1, R2, R3, a winding DR1, the motor armature 1, an overload relay OL, an ammeter 4, isolating switch IS to L -. The shunt 2 is also energized. The motor starts at a slow speed, the closure of switch C short-circuits the resistance Rl and the field 3, and the closure of switches D, E shortcircuits the resistances R2, R3 thus speeding up the motor in steps. The shunt field circuit is from L+, through switch IS, line 5, field windings 2, control element HSR, line 6, winding OL &c. to L-. A master controller is provided having a bridging contact 8 which is moved over fixed contacts to effect making and breaking of the circuits in a proper sequence. In the first position, after the reset push 9 has been depressed, a circuit is established through the winding of switch A, switch IS, fuse 10, normally closed, interlocks Ia2, Ibl, through push 9, conductor 11, contact 12, bridge 8. contact 13, line 14, winding of switch A, normally closed interlock IR3 in transition winding IR, conductors 15,16, interlock FF1 of shunt field control element HSR, through interlock Ie2 on switch E, overload relay contacts OL, stop push 17, fuse 18, and switch IS to L-. It is impossible to close the switch A unless the shunt field is fully energized. Upon closure of the switch A, the interlock Ia2 breaks circuit through and shorts the push 9 and maintains the switch A. Established simultaneously with the energization of winding A is a circuit for the winding VRC of a voltage drop relay, and the contacts VR1 are as shown only when the frictional, resistance of the engine is reduced to a given degree. This danger point over, the controller may be moved to other positions without the winding of A being de-energized, otherwise a restart must be made. When the contacts VR1 move, the lamp IL1 is extinguished. When small engines are under test, a diverter resistance R4, R4+ is connected in shunt to the armature by closing of switch G which is energized when drum is at first position through a hand switch SS in parallel with winding of A. The part R4 which is variable is subsequently employed in the power absorption test. The resistance 49 in series with the winding VRC of the voltage drop relay is short-circuited when switch G is closed bv the interlock Ig1. This is to adjust the point of response of relay VR1 to suit conditions occasioned by R4 being in operation. In position 2 of the controller, the circuit of winding G is broken and the resistance R4 cut out if employed. In the position 2A of the controller, an energizing circuit is established for the winding of switch C and the resistance R1 and field 3 are cut out. In positions 3, 4, the switches D, E are energized, and resistances R2, R3 cut out. Regenerative stage.-Fuel supply and ignition for the engine is now started, the circuits remaining the same. The controller is next moved to the transition position. The circuit of winding E remains energized, but additional circuits through relay IR upon simultaneous closure of BO, DR, the latter being controlled by a differential winding DR1, DR2. The switch DR is closed when current is fed to the mains and is within 5 per cent of the transition value. The contacts BO close at the transition value. The pilot lamp IL2 is illuminated immediately the controller is moved to position T. The winding IR operates IR1 to break circuit and make an independent circuit through line 38. The energization of winding IR opens IR3, breaks circuit of switch A and of lamp IL3. Circuit of C, D, E are also broken. The circuit of IR and lamp IL2 is now independent of switch FF1 so that the shunt field may be reduced without deenergization of relay IR. The switch B closes and resistances R1 .. R4 are in series across the dynamo armature. The series field 3 is now connected in series with resistances R1-R3 and in parallel with the resistance R4 so that current flows through the field in the same direction as before. In positions 5, 6, 7 the coils C, D, E are energized for cutting out resistances R1, R2, R3. The engine is provided with a magneto 44 and coil 45 energized by battery 46. The operation is controlled by interlocks Ia1, IR2. During the regeneration, the magneto will be disconnected from " Earth " and will be capable of functioning. When the system is not working the magneto is earthed and circuit of the coil 45 broken. When moved beyond position 7, the circuit of the coil is broken and the magneto earthed. The contacts of OL being always in the circuits of A, C, D, E and IR, but not in circuit of B, upon overload, the switch A must open cutting off the armature from the mains while C, D, E put full resistance in the armature circuit, the winding B will be closed and the magneto earther and coil circuit broken.